Patent GB-467573-A (GB)
Title: Improvements in or relating to thermionic valves
IPC: H01J31/04
Filed: 1935-12-16
Abstract: 467,573. Cathode-ray tubes; valve amplifying circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., RUST, N. M., and BRETT, G. F. Dec. 16, 1935, Nos. 34883 and 34885. [Classes 39 (i) and 40 (v)] An electron beam valve has a collector electrode positioned to receive electrons which do not impinge on an anode which is a single electrode slotted or so shaped that the amount of the cross-section of the beam intercepted by it may be varied by deflecting the beam or by varying its cross-section, so that any part of the beam not intercepted by the anode falls on the collector electrode and a smooth and quantitative control of the shares of current taken by the anode and collector electrode may be obtained. Such a valve may have a straight control electrode-anode voltage characteristic, or a negatively sloping anode voltageanode current characteristic. As shown, an anode 5, Fig. 5, with a central slot 5a is mounted in front of a collector electrode 6, Fig. 4, and a slotted control electrode 2, a slotted accelerator anode 3, a slotted screening electrode 4, and deflecting plates 7, 8 are mounted between a straight indirectly-heated cathode 1 and the anode 5, the slots being of the same length as the cathode. The collector electrode is maintained at a higher potential than the anode. When used as a low-frequency amplifier as shown in Fig. 4, the input is connected between the control electrode 2 and the cathode 1, and the deflector plate 7 is connected directly with the cathode, and the other deflector plate 8 is connected with the cathode through a resistance 10. The potential difference across the deflector plates thus depends on the total current through the valve, and the resulting deflection of the beam with increasing current serves as a correction by causing a part of the beam to pass through the slot to the collector electrode ; or the deflection may be made to depend on the anode current alone. In the arrangement shown in Fig. 12, the deflector plates are dispensed with, and the control electrode 2 is of cylindrical shape with a slot parallel with the axis of the cathode 1. The beam passes through a focal line or area, and by varying the position of the focal line &c. the amount of the beam passing through the slot 5a in the anode 5 may be varied. Thus by increasing the anode voltage most of the beam passes through the slot and a negative characteristic is obtained. The beam may be surrounded by a flattened cylinder for controlling the shape of the characteristic, or focusing control may be obtained by an electrostatic or electromagnetic electron lens system. Dimensions are given. In the high-frequency amplifier shown in Fig. 9, the indirectly-treated cathodes 1 of the valves V1, V2 are earthed, and the input circuit 13 of the first valve V<1> is connected between the control electrode 2 and the cathode 1, the deflecting electrode 7 and the screening electrode 4 being connected with the cathode. The slotted anode 5 is connected with a source of potential through a tuned circuit 18 and a choke 19 of high impedance to the frequencies to be amplified. A condenser 20 of low impedance to the frequencies to be amplified, is connected between the choke 19 and a resistance 10 connected with the cathode. The anode of the valve V<2> is connected similarly. The resistance 10 may be replaced by a flatly tuned network consisting of an inductance shunted by a resistance and by a condenser, Fig. 10 (not shown), or by a network consisting of an inductance 10L<1>, Fig. 11 shunted by a resistance 10R<1> in series with a capacity 11C<11> shunted by a resistance 10R<11>. Specifications 403,973 and 462,035 are referred to.